What percentage of the stars produce black holes?

In the young cosmos, collisions between protogalaxies lead to the rapid formation of black holes with billions of times the mass of the sun

Excerpt from the simulation

Zurich (Switzerland) - So far, it has been a mystery to astronomers: Less than a billion years after the Big Bang, there were black holes in the cosmos with billions of times the mass of the sun. They act as power plants for quasars, extremely luminous radiation sources in galaxy nuclei. How could such supermassive objects come into being so quickly? An international team of researchers is now presenting computer simulations in the journal "Nature" that show a solution to this dilemma: collisions between galaxies generate unstable gas clouds that rapidly collapse into super stars and finally into massive black holes.

In the young cosmos, according to the initial idea of ‚Äč‚ÄčLucio Mayer from the University of Zurich and his colleagues from Switzerland, the USA and Chile, collisions and mergers of protogalaxies play an important role. With their simulations, the astrophysicists pursued the question of what happens to the gas in these cosmic catastrophes. The team's calculations show that a supermassive gas disk forms in the center of the merging protogalaxies, which is in a highly unstable state. Spiral currents develop in the gas disk, which transport over 100 million solar masses of gas to the center of the disk within 100,000 years. The core of the dense gas cloud that accumulates in this way then collapses into a super star with tens of thousands of solar masses, which develops rapidly and produces a massive black hole in a final core collapse.

The decisive factor here is that the entire process takes place extremely quickly from a cosmological point of view: the time scale is considerably shorter than the typically 100 million years that would be necessary for stars to form in the gas disk. After the formation of the massive black hole, there is still a large amount of gas available that will allow the black hole to grow into a super massive giant in a few hundred million years. The weakness of previous explanations was that they required very special conditions to prevent the formation of stars in the gas clouds from which the black holes form.

The scenario simulated by Mayer and his colleagues has so far only worked for protogalaxies that are already very massive and from which large galaxies arise. Supermassive black holes have also been detected in the centers of dwarf galaxies that contain less than a hundredth of the mass of the Milky Way. It is possible that the black holes in the dwarf galaxies were formed by another process, perhaps from the remains of the first generation of stars. Future instruments such as the James Webb Space Telescope, the X-ray satellite IXO and the gravitational wave detector LISA stationed in space could give astronomers the opportunity to directly observe the formation phase of the supermassive black holes.